Contact sensors for sensing and measuring opposing forces at a plurality of locations, and systems for using them are disclosed in U.S. Pat. Nos. 4,734,034 and 4,856,993. Such sensors broadly comprise a pair of backing sheets, each with a set of parallel electrodes, with the sets of parallel electrodes in a facing, crossing pattern, thereby providing a plurality of closely adjacent intersections. A resistive, semiconductive material is disposed between the facing electrodes at each intersection. As such a variable output from the sensor depending upon the relative force applied may be obtained at each intersection. Typical materials used to form such sensors, their dimensions, the associated reader heads, etc., are all described in the above patents, the disclosures of which are here incorporated by reference.
Although careful efforts may be employed to make each contact sensor exactly uniform across its operating sensing zone, namely at each relevant intersection of the crossing electrodes, it will be apparent that slight differences in thicknesses of the materials across their widths and along their lengths, as well as discontinuities and differences in the thicknesses and characteristics of the deposits of the resistive material at the intersections of the sets of electrodes will produce pluralities of intersections which are somewhat non-uniform in their outputs for a given applied force. Furthermore, such non-uniformities may well vary with the applied force.
Where contact sensors of these types are to be used to measure applied forces closely or accurately, as distinguished, for example, from sensing contact versus non-contact, it becomes desirable and necessary to calibrate each contact sensor so that its varying characteristics at the plural intersections may be determined. Thereafter, when a contact sensor is used to provide accurate representations of differing loads applied at the intersections, the differences attributable to the differences in the intersections themselves may be taken into consideration and eliminated as variables. As such, a calibration fixture and method for facilitating accurate calibration would be desirable.